Power system for multi-pressure hydraulic press

ABSTRACT

The subject of the present invention is a power system for a double-acting hydraulic press equipped with power cylinders and plungers whose motion is coupled together, these cylinders with plungers being situated outside of both working zones of the press. Each cylinder and plunger is of a different diameter; i.e., obtained are several different working faces of plungers, and several different displacement volumes. In the effect of such a design a whole series of pressures and press operation frequencies can be obtained in a press under constant parameters of the hydraulic system, namely the pressure and the delivery of the pumped liquid, for selecting in the press the optimum pressures and operation frequencies required for a particular working process. In this way a double-acting press equipped with the invented multi-pressure systems eliiminates the whole series of conventional hydraulic presses.

United States Paten Nowak Nov. 12, 1974 1 POWER SYSTEM FOR MULTl-PRESSURE Primary Examiner-Harvey C. Hornsby HYDRAULIC PRESS [75] Inventor:

Edmund Nowak, Warszawa, Poland Filed: Aug. 17, 1972 Appl. No.: 281,389

Assignee:

[30] Foreign Application Priority Data Nov. 9, 1971 Poland 150463 [56] References Cited UNITED STATES PATENTS 6/1942 Humphrey 100/269 R X 8/1948 Renier 100/214 UX FOREIGN PATENTS OR APPLlCATlONS 411,413 6/1934 Great Britain 100/209 Assistant ExaminerPhilip R. Coe Attorney, Agent, or Firm-Edwin E, Greigg [57] ABSTRACT The subject of the present invention is a power system for a double-acting hydraulic press equipped with power cylinders and plungers whose motion is coupled together, these cylinders with plungers being situated outside of both working zones of the press.

Each cylinder and plunger is of a different diameter; i.e., obtained are several different working faces of plungers, and several different displacement volumes. In the effect of such a design a whole series of pressures and press operation frequencies can be obtained in a press under constant parameters of the hydraulic system, namely the pressure and the delivery of the pumped liquid, for selecting in the press the optimum pressures and operation frequencies required for a particular working process.

In this way a double-acting press equipped with the invented multi-pressure systems eliiminates the whole series of conventional hydraulic presses.

8 Claims, 1 Drawing Eigure POWER SYSTEM FOR MULTI-PRESSURE HYDRAULIC PRESS The subject of the present invention is a power system for a double-acting, multi-pressure hydraulic press.

The single or double-acting hydraulic presses used at the present time are fitted, in general, with single stage power pistons or plungers, namely with pistons or plungers having only a single working face.

Also known are hydraulic presses powered by twostage plungers namely the plungers having two faces, with each facing against the direction of the working stroke, these plungers working in two-stage cylinders.

In the constructions of such design the smaller face of a plunger gives a small displacement volume, this volume serving for a so-called priming of the cylinder namely for filling the cylinder with hydraulic liquid under a minimum pressure, and for a quick travel of the plunger to the working zone; on the larger face of the plunger, or on the sum of both faces of the plunger, acts, or on the other hand, the hydraulic liquid under a high pressure, thus allowing to obtain high technology pressures for the press, these high pressures being required for the working operation over a short distance of piston stroke in the working zone.

The fundamental drawback of power systems for hydraulic presses with a single-stage plunger is the necessity of using the pumps of a high delivery of the pumped hydraulic liquid, this high delivery being required for a quick travel of the plunger to the working zone in which, in turn, the travel of the plunger is several times smaller than the idle stroke, owing to the fact that the press performs then a working operation, and therefore the liquid demand becomes then considerably smaller. The pump, however, is delivering the constant in time quantities of liquid, and therefore the liquid surplus is forced, through a relief valve, to the tank, this resulting in well known disturbances in the hydraulic system. In order to prevent these disturbances the pumps of vari- 'able delivery and pressure were used, namely the pumps in which the quantity and the pressure of the pumped liquid are automatically suited to the speed of the plunger travel and to the resistance of its motion, i.e., to the technology pressures prevailing in the working zone of the press. Such a solution was only partially successful for obviating the above-mentioned problems, and application of expensive pumps of variable delivery is unfavorably affecting the cost of the whole press.

Application of two-stage cylinders and plungers whose smaller displacement volume can be quickly filled with hydraulic liquid from a special low pressure priming tank, allows that small pumps can be used of a small delivery and of a high pressure acting upon both working faces; however, a hydraulic power system of such type is intricate and complex. Finally, the common shortcoming evident in power systems of both types is a limited possibility of adjusting the frequency of plunger operation and of its working pressures. From the technology point of view quite a number of metal sheet plastic worked elements can be made under various working pressures and at different operation frequencies, and therefore a press is required with a power system allowing to alter these parameters within a wide 7 range. The pumps with the delivery and pressure automatically regulated according to the load allow the press operation frequency to be altered within a comparatively small range. The priming systems, on the I other hand, including a low pressure tank are suitable only for the presses of a small operation frequency. Similar problem arises in the case of double-acting presses having two working zones: a top zone, and a bottom zone. The economy aspects are prompting that during a working cycle the use is made of both these working zones or levels, while the technical factors allow that realized also can be-two different pressures depending on the type of produced element and on the type of operation in a given zone. The pumps of a constant delivery, and consequently of a constant pressure, applied in the automatic double-acting presses,are ruling out the possibility of application of two different pressures, the systems including a priming tank are not at all suitable for application in the presses of this type, while the pumps of a variable delivery and pressure are only partially able to satisfy this requirement.

The purpose of the present invention is to obviate the above-mentioned inconveniences by developing a hydraulic power system for a double-acting press, this system allowing, under application of a constant delivery pump, to obtain various pressures in the press, and to alter its operation frequency within a possibly wide range.

The assumed technical problem has been solved in such a manner, that the coupled together power plungers of the power system of a double-acting hydraulic press, these plungers being located outside the both working zones of the press, are provided with several working faces.

The fundamental noteworthy feature of such a hydraulic system is the possibility of obtaining, under the application of only a single pump of constant delivery and pressure, of various working pressures in both zones, and of various operation frequencies. Namely, at a defined value of plunger stroke several displacement volumes canbe obtained depending on the number of working faces on the plunger. The liquid directed to the cylinder and, by means of a distributor device, beneath one of the plunger working faces causes that a particular displacement volume and, at the same time, a particular operation frequency is selected; the magnitude of the pressure is the effect of the area of selected working face and of the value of the pressure. This means that as a result of directing the liquid to the cylinder, and beneath the different working faces of plungers, obtained are different operation frequencies and different pressures of the press and that different pressures, not equal to each other, can be obtained in each working zone. For example, if two plungers are employed, each plunger having two different working faces, obtained together in both working zones are nine combinations of pressures and therefore nine frequencies of operation. I

The subject of the present invention is shown in the drawing in which the FIGURE illustrated is the invented power system mounted on a double-acting hydraulic press.

As it is seen in the FIGURE, the power system for a double-actingpress consists of plungers 1a and 1b, said plungers being'provided with several different working faces and operating in cylinders 2a and 2b, said cylinders being mounted on the top and bottom part of a press frame 3. The bottoms of the said cylinders are attached, by means of bolts (not shown in the drawing) to the top and bottom part of the said frame. Columns 4 slide in the frame 3, and a platen 5 is rigidly fixed to the said columns. Attached to the said columns, by means of nuts, are plates 6a and 6b which operate jointly with plungers 1a and 1b. Bolted to the cylinders are ring gears 8a and 8b, said rings being meshed with worm screws 7a and 7b, said worm screws being the provision for adjusting the stroke of the said plungers.

The power system operates as follows:

To the cylinder 2b the liquid is fed, for instance through the aperture 0, to the zone beneath the working face of plunger 1b, thus effecting a downward motion of an assembly consisting of plunger 11;, plate 6b, columns 4, platen 5, plate 6a, and plunger la, until the working operation, under the pressure of the press, takes place in the bottom working zone of the press, this pressure being the product of a given face area of the plunger and of the pressure of the liquid.

Next, the distributing device directs the liquid, for instance through the aperture A, to the zone beneath the working face of plunger 1a, and the whole previously mentioned assembly moves upward, until in the top working zone of the press the working operation takes place under the pressure whose value is the effect of a given area of the plunger working face and of the liquid pressure which has a constant value. In this way two different pressures are obtained in a single cycle. A suitably programmed distributing device is arranged to control the flow of liquid to the zone beneath one, or simultaneously various, working faces of plungers 1a and 1b, thus causing various pressures of the press, and various frequencies of press operation to be obtained.

What is claimed is:

1. A double-acting hydraulic press having two pressing stations comprising, in combination:

a. a first power cylinder;

b. a first plunger positioned in said first power cylinder, said first plunger having a first plurality of working faces to which hydraulic fluid may be independently applied;

c. means for selectively supplying hydraulic fluid to said first power cylinder and thence selectively to at least one of said first plurality of working faces;

d. a platen positioned between said two pressing stations and having a first and a second working surface;

e. coupling means coupling said platen to said first plunger;

f. a second power cylinder;

g. a second plunger positioned in said second power cylinder, said second plunger having a second plurality of working faces to which hydraulic fluid may be independently applied;

h. means for selectively supplying hydraulic fluid to said second power cylinder and thence selectively to at least one of said second plurality of working faces; and

i. further coupling means for coupling said platen to said second plunger;

whereby various pressures for the press may be effected by selectively supplying hydraulic fluid to one or simultaneously more than one of said working faces to move said platen selectively and alternatively into one and the other of said pressing stations.

2. A double-acting hydraulic press as defined in claim 1, wherein said first plurality of working faces is composed of at least two working faces having respectively different areas.

3. A double-acting hydraulic press as defined in claim 2, wherein said second plurality of working faces is composed of at least two-working faces having respectively different areas.

4. A double-acting hydraulic press as defined in claim 1, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas.

5. A double-acting hydraulic press as defined in claim 1, further comprising a monolithic frame having two spaced-apart, rigid structural members, each of said members having a surface facing inwardly and a surface facing outwardly, said inwardly facing surfaces being working surfaces of respective ones of said two pressing stations, said outwardly facing surfaces having respective ones of said first power cylinder and said second power cylinder mounted thereon, and said platen being positioned between said structural members.

6. A double-acting hydraulic press as defined in claim 5, wherein said first plurality of working faces is composed of at least two working faces having respectively different areas.

7. A double-acting hydraulic press as defined in claim 6, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas.

8. A double-acting hydraulic press as defined in claim 5, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas. 

1. A double-acting hydraulic press having two pressing stations comprising, in combination: a. a first power cylinder; b. a first plunger positioned in said first power cylinder, said first plunger having a first plurality of working faces to which hydraulic fluid may be independently applied; c. means for selectively supplying hydraulic fluid to said first power cylinder and thence selectively to at least one of said first plurality of working faces; d. a platen positioned between said two pressing stations and having a first and a second working surface; e. coupling means coupling said platen to said first plunger; f. a second power cylinder; g. a second plunger positioned in said second power cylinder, said second plunger having a second plurality of working faces to which hydraulic fluid may be independently applied; h. means for selectively supplying hydraulic fluid to said second power cylinder and thence selectively to at least one of said second plurality of working faces; and i. further coupling means for coupling said platen to said second plunger; whereby various pressures for the press may be effected by selectively supplying hydraulic fluid to one or simultaneously more than one of said working faces to move said platen selectively and alternatively into one and the other of said pressing stations.
 2. A double-acting hydraulic press as defined in claim 1, wherein said first plurality of working faces is composed of at least two working faces having respectively different areas.
 3. A double-acting hydraulic press as defined in claim 2, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas.
 4. A double-acting hydraulic press as defined in claim 1, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas.
 5. A double-acting hydraulic press as defined in claim 1, further comprising a monolithic frame having two spaced-apart, rigid structural members, each of said members having a surface facing inwardly and a surface facing outwardly, said inwardly facing surfaces being working surfaces of respective ones of said two pressing stations, said outwardly facing surfaces having respective ones of said first power cylinder and said second power cylinder mounted thereon, and said platen being positioned between said structural members.
 6. A double-acting hydraulic press as defined in claim 5, wherein said first plurality of working faces is composed of at least two working faces having respectively different areas.
 7. A double-acting hydraulic press as defined in claim 6, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas.
 8. A double-acting hydraulic press as defined in claim 5, wherein said second plurality of working faces is composed of at least two working faces having respectively different areas. 